The present invention relates to a consumer electronics apparatus for transmitting information by wireless means, and more particularly to an apparatus using a metal casing as an antenna.
It is recently attempted to use an information consumer electronics apparatus such as a set-top box by connecting to a network by wireless means:
A conventional example of wireless information consumer electronics apparatus is shown in FIG. 13 and FIG. 14. In the conventional wireless information consumer electronics apparatus shown in FIG. 13, an antenna 301 was used as an independent component. The antenna 301 was usually installed, for example, on the back side 302 of the apparatus or top 304 of the metal casing 303, because it must be installed in a place accessible to the space and not interfering the handling operation of the wireless information consumer electronics apparatus.
In the conventional method, however, if the antenna is installed in other places than the back side 302 of the apparatus or top 304 of the metal casing 303, depending on the direction of installation of the apparatus making communication, the following happens.
As shown in FIG. 14, even if transmitted and received waves of two apparatuses are in the same polarization plane, the reception power is lowered, and the antenna mounting position is limited.
Further, in the conventional method, when the antenna is installed at the position on the top 304 of the apparatus as shown in FIG. 13, the radiation directivity characteristic of the antenna is as shown directions 305, 306, and 307 in FIG. 14. Then the sensitivity is insufficient and the communication distance is short in the direction of 308. Consequently the position of installation of the apparatus is limited.
Besides, in the conventional method, when a plurality of information consumer electronics apparatuses such as set-top boxes are stacked up, the metal casing of each set-top box may impair the antenna characteristic of other set-top box, and the communication area is limited, or the communication distance is shortened.
Addressing to the problems, the wireless information consumer electronics apparatus of the invention comprises:
a) a metal casing used as an antenna, the metal casing being in a shape to resonate at the frequency being used,
b) a radio frequency module having a current feeding terminal for transmitting radio frequency signal or receiving radio frequency signal mounted on the outer surface of the casing, and
c) current feeding coupling means for feeding radio frequency current from the current feeding terminal to the outer surface of the metal casing through a mounting screw of the radio frequency module, and coupling the radio frequency module mechanically to the metal casing.
The wireless information consumer electronics apparatus in other aspect of the invention comprises:
a) a metal casing used as an antenna, the metal casing being in a shape to resonate at the frequency being used,
b) a radio frequency module installed inside the metal casing, and
c) means for feeding radio frequency current to the outer surface of the metal casing through a grounding wire of the radio frequency module connected in direct current to the metal casing and a current lead-out notch provided in the metal casing.
The wireless information consumer electronics apparatus in a different aspect of the invention comprises:
a) a metal casing used as an antenna, the metal casing being in a shape to resonate at the frequency being used,
b) a radio frequency module installed inside the metal casing, and
c) means for feeding radio frequency current to the outer surface of the metal casing through an excitation patch of the radio frequency module connected electromagnetically to the metal casing and a current lead-out window provided in the metal casing.
The wireless information consumer electronics apparatus in another aspect of the invention comprises:
a) a metal casing in a shape to resonate in plural modes at the frequency being used, and
b) means for feeding radio frequency current to the casing in plural excitation modes, so that the metal casing may operate in polarization and directivity diversity action.
The wireless information consumer electronics apparatus of the invention further comprises means for generating the plural excitation modes by selecting two or more grounding wires out of at least three or more grounding wires.
The wireless information consumer electronics apparatus of the invention further comprises means for generating the plural excitation modes by using plural resonance modes of the excitation patch.
The wireless information consumer electronics apparatus in a further aspect of the invention comprises:
a) a metal casing used as an antenna, and
b) an antenna automatic matching device for automatically detecting presence or absence of metal in the surroundings, or metal approaching state by monitoring the matching state of the antenna, and matching the antenna by varying the impedance of an antenna matching element automatically by a detection signal of the matching state.
In the wireless information consumer electronics apparatus of the invention, a varactor diode is used as the antenna matching element.
In the wireless information consumer electronics apparatus of the invention, a ferrodielectric capacitor is used as the antenna matching element.
According to the invention, by using a metal casing as an antenna, an independent component as antenna is not used, so that a wireless information consumer electronics apparatus not limited in the mounting position of antenna is realized.
According to the invention, a wireless information consumer electronics apparatus less limited in the place of installation of the apparatus is realized.
According to the invention, for example, even when stacking up a plurality of information consumer electronics apparatuses such as set-top boxes, the wireless information consumer electronics apparatus is less limited in the communication area and the communication distance is less shortened.